Hideo Kojima has put out an explanation of some of the confusion generated from yesterday’s presentation. As seen on @hideo_kojima_EN:
"Ground Zeroes" is a prologue of "MGSV". 9 years after that event will be "The Phantom Pain". MGSV is constructed w/ prologue and main game "TPP". The game play demo I presented today is the opening of "TPP" which is tutorial that starts from crawling.